This invention relates to an apparatus for stacking and intermittently discharging the stacks of sheets for electrical machines and the like. More specifically, this invention relates to such apparatus of the type including a plurality of stacking mandrels and mandrel moving means for successively moving the mandrels into and out of sheet receiving positions at a delivery zone of a conveyor which continuously successively supplies the sheets. With this type of apparatus, in order to avoid interruption of the conveyor or the stacking process, some type of intermediate stacking means are needed to accommodate an exchange of mandrels.
Such an apparatus is shown, for example, in DAS (German Published Application) 2,019,661. In the process of using this apparatus, the sheets, worked on by a high-speed automatic punching machine, are transferred in a partially overlapping position to a magnetic conveyor belt. A roller is arranged at the delivery end of the magnetic conveyor belt. This roller holds the respectively subsequent sheet at its rearward end -- as seen in the conveying direction -- against the magnetic conveyor belt, even if the sheet has already left the belt for the largest part. This roller engages the sheet as the same is passing on to a mandrel constituting a main stacking device. Respectively one of several mandrels arranged on a stepwise-rotating turntable is located underneath the delivery end of the conveyor belt, so that the sheets, after being released by the roller, arrange themselves on a mandrel and form a main stack. As soon as the main stack is filled, an intermediate stacking device is suddently moved under the delivery end of the magnetic belt conveyor, and the sheets which have been fed continuously are stored temporarily in the intermediate stacking device, fashioned as a collecting trough, while the mandrel, filled up by the main stack, is replaced by an empty mandrel by a further stepwise rotation of the turntable. Once this has been done, the sheets in intermediate storage are delivered to the empty mandrel and the intermediate stacking device is simultaneously swiveled out of the range of the delivery end of the magnetic conveyor belt. The formation of a new main stack on the basis of the intermediate pile can now proceed unhindered.
To obtain a secure reception and an improved alignment of the sheets during the short time interval of intermediate stacking, it has already been proposed in DOS (German Unexamined Laid-Open Application) 2,037,752 to provide the intermediate stacking device with stops and/or mountings, which align the sheets with respect to the mandrels of the main stacking device.
By means of these measures, an improvement of the intermediate stacking device has been made possible with regard to the reception and alignment of the sheets, but an optimum solution is only provided by the present invention, which relates, in an apparatus of the type described hereinabove, to attaining an intermediate stacking of the sheets with an exact centering and positioning with respect to a specific groove pattern.
According to preferred embodiments of the present invention, the intermediate stacking device is fashioned as a mandrel tip positionable at the delivery end of the conveyor in axial alignment with respective ones of the mandrels when the mandrels are in their respective sheet receiving positions. Holding means are provided for holding the mandrel tip in position to form an intermediate stack of sheets during exchange of mandrels. Once a new empty mandrel is disposed beneath the mandrel tip, the intermediate stack is released onto the mandrel and the stacking process continues with the sheets passing over the mandrel tip onto the mandrel being filled.
The advantages of the invention are to be seen, inter alia, in the fact that even during the exchange of a fully stacked mandrel against an empty mandrel the continuously delivered sheets are piled up in an exactly centered and positioned fashion, forming an intermediate stack, on a mandrel tip.
A simple, exact, and rapid coaxial operative connection can be produced during a mandrel change by fashioning the upper ends of the mandrels arranged on the stepwise-rotating turntable as an external cone and the lower end of the mandrel tip, which is only required in singular, as an internal cone.
A further advantage is attained according to preferred embodiments by connecting the holding means with a movable slide bounding the intermediate pile, this slide encompassing the mandrel tip in the manner of a fork. The holding means is arranged, as seen in the stacking direction, underneath the slide, whereby the opening and closing paths of the holding jaws of the holding means can be maintained to be very short.
These and further objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, a single embodiment in accordance with the present invention.